CN111511857B - Adhesive sheet and method for producing laminate - Google Patents

Adhesive sheet and method for producing laminate Download PDF

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Publication number
CN111511857B
CN111511857B CN201880081861.3A CN201880081861A CN111511857B CN 111511857 B CN111511857 B CN 111511857B CN 201880081861 A CN201880081861 A CN 201880081861A CN 111511857 B CN111511857 B CN 111511857B
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adhesive sheet
pressure
sensitive adhesive
meth
sheet
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CN111511857A (en
Inventor
黑田大辅
瀬口诚司
清水滋吕
伊藤万智
大里竜也
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Oji Holdings Corp
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Oji Holdings Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/16—Layered products comprising a layer of synthetic resin specially treated, e.g. irradiated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/10—Adhesives in the form of films or foils without carriers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/40—Adhesives in the form of films or foils characterised by release liners
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
    • C09J2301/416—Additional features of adhesives in the form of films or foils characterized by the presence of essential components use of irradiation

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Adhesive Tapes (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Laminated Bodies (AREA)

Abstract

The present invention addresses the problem of providing an adhesive sheet that has both level difference following properties, durability, and handling properties. The present invention relates to a pressure-sensitive adhesive sheet having photocrosslinkable properties, wherein the pressure-sensitive adhesive sheet has a tensile stress of 0.3N/mm at a tensile elongation of 2000% before photocrosslinking 2 The tensile elastic modulus before photocrosslinking is 150kPa to 300kPa, and the b/a ratio is less than 3.0 when the tensile elastic modulus before photocrosslinking is a and the tensile elastic modulus after photocrosslinking is b.

Description

Adhesive sheet and method for producing laminate
Technical Field
The present invention relates to a method for producing an adhesive sheet and a laminate.
Background
In recent years, input devices used in combination with display devices such as Liquid Crystal Displays (LCDs) and display devices such as touch panels have been widely used in various fields. In the manufacture of these display devices and input devices, a transparent double-sided adhesive sheet is used for the purpose of bonding optical members, and a transparent double-sided adhesive sheet is also used for the purpose of bonding the display devices and the input devices.
The touch panel and the liquid crystal display may include a component having a height difference caused by printing or the like. For example, a touch panel having a frame-shaped printed member is used in a mobile phone. In such applications, the pressure-sensitive adhesive sheet is required to have a property of bonding and fixing members (adhesiveness) and a property of filling and printing a level difference (level difference following property).
For example, patent document 1 proposes a post-curing adhesive sheet which is a hot-melt adhesive sheet having a property of easily following a level difference by heating the adhesive sheet, wherein the adhesive sheet is post-cured by irradiating an active energy ray after following the level difference, thereby improving the adhesiveness. Pressure-sensitive adhesive sheets that can achieve both adhesiveness and level difference following properties have been developed.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2016-222916
Disclosure of Invention
Problems to be solved by the invention
Touch panels and liquid crystal displays are sometimes exposed to a severe environment such as high temperature and high humidity. Therefore, there is a demand for an adhesive sheet that does not change the adhesive performance or the like even under a severe environment such as high temperature and high humidity. That is, the adhesive sheet is also required to have durability under severe environments. However, the conventional post-curing adhesive sheet has a problem that the level difference following property is insufficient when the durability is improved.
Further, the conventional post-curing adhesive sheet has the following problems: when it is desired to improve the level difference following property, the adhesive may be accidentally diffused at the time of bonding, and the handling property at the time of bonding may be poor.
In order to solve the problems of the prior art, the present inventors have made studies with an object of providing a pressure-sensitive adhesive composition having both level difference following properties, durability and handling properties.
As a result of intensive studies to solve the above problems, the present inventors have found that a pressure-sensitive adhesive sheet having photo-crosslinkability and having satisfactory level difference following properties, durability and handling properties can be obtained by setting the tensile stress and tensile elastic modulus at a tensile elongation of 2000% before photo-crosslinking to a predetermined range and further setting the ratio of the tensile elastic modulus before photo-crosslinking to the tensile elastic modulus after photo-crosslinking to a predetermined range in a post-curing type pressure-sensitive adhesive sheet having photo-crosslinkability.
Specifically, the present invention has the following configuration.
[1] An adhesive sheet having photo-crosslinking properties,
the adhesive sheet has a tensile stress of 0.3N/mm at a tensile elongation of 2000% before photocrosslinking 2 In the following, the following description is given,
the tensile elastic modulus before photocrosslinking is 150kPa to 300kPa,
when the tensile elastic modulus before photocrosslinking is represented by a and the tensile elastic modulus after photocrosslinking is represented by b, b/a is less than 3.0.
[2] The adhesive sheet according to [1], which comprises a (meth) acrylic copolymer having a glass transition temperature (Tg) of-50 ℃ to-40 ℃ and a weight-average molecular weight of 25 to 45 ten thousand.
[3] The pressure-sensitive adhesive sheet according to [1] or [2], wherein the gel fraction before photocrosslinking is 5.0% or less, and the gel fraction after photocrosslinking is 50% or more.
[4] The adhesive sheet according to [2] or [3], wherein the adhesive sheet comprises 0.1 to 6 parts by mass of a polyfunctional monomer and 0.1 to 10 parts by mass of a photopolymerization initiator which initiates polymerization of the polyfunctional monomer by light irradiation, based on 100 parts by mass of the (meth) acrylic copolymer.
[5] The adhesive sheet according to any one of [1] to [4], wherein the thickness is 50 to 200 μm.
[6] A double-sided pressure-sensitive adhesive sheet with a release sheet, which comprises a release sheet on both sides of the pressure-sensitive adhesive sheet according to any one of [1] to [5 ].
[7] A method for producing a laminate, comprising the steps of: a bonding step of bringing the pressure-sensitive adhesive sheet according to any one of [1] to [5] into contact with an adherend surface, and a light irradiation step.
[8] The method for producing a laminate according to [7], wherein the adherend is an optical member.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a pressure-sensitive adhesive sheet having a level difference following property, durability and handling property can be obtained.
Drawings
Fig. 1 is a sectional view showing an example of the structure of a double-sided adhesive sheet with a release sheet according to the present invention.
Fig. 2 is a sectional view showing an example of the structure of the laminate.
Detailed Description
The present invention will be described in detail below. The technical features described below may be described based on a representative embodiment and a specific example, but the present invention is not limited to such an embodiment. In the present specification, a numerical range expressed by using "to" means a range including numerical values described before and after "to" as a lower limit value and an upper limit value. Further, "(meth) acrylic" is meant to include both acrylic and methacrylic.
(adhesive sheet)
The present invention relates to a pressure-sensitive adhesive sheet having photocrosslinkable properties. In the adhesive sheet of the invention, the tensile stress at a tensile elongation of 2000% before photocrosslinking is 0.3N/mm 2 The tensile elastic modulus before photocrosslinking is 150kPa to 300kPa, and the b/a ratio is less than 3.0 when the tensile elastic modulus before photocrosslinking is a and the tensile elastic modulus after photocrosslinking is b.
The pressure-sensitive adhesive sheet of the present invention has the above-described structure, and therefore has both level difference following properties, durability, and handling properties. The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having photocrosslinkable properties, and can follow a level difference of an adherend without a gap before photocrosslinking. On the other hand, the photo-crosslinked resin composition exhibits sufficient durability. In the present invention, by optimizing the tensile stress and tensile elastic modulus of the pressure-sensitive adhesive sheet, both the level difference following property and the durability are achieved, and the handling property of the pressure-sensitive adhesive sheet is successfully improved. The adhesive sheet of the present invention contains substantially no thermal crosslinking agent. When the adhesive sheet of the present invention does not contain a thermal crosslinking agent, the curing step can be omitted when forming the adhesive sheet, and the time required for producing the adhesive sheet can be shortened.
The pressure-sensitive adhesive sheet of the present invention exhibits excellent step following properties. The pressure-sensitive adhesive sheet of the present invention can follow a height difference of 35 μm or more without a gap even when the pressure-sensitive adhesive sheet has a height difference in the bonded portion, and in such a case, it can be evaluated that the height difference following property is excellent. The adhesive sheet of the present invention is also excellent in durability. Specifically, even when the pressure-sensitive adhesive sheet of the present invention is attached to a level difference portion and ultraviolet rays are repeatedly irradiated under the following conditions, the pressure-sensitive adhesive sheet does not undergo deterioration and does not cause bubbles or the like. The ultraviolet irradiation condition is set to 0.8W/m, for example 2 At 80 ℃ for 4 hours and at 0.53W/m 2 1 cycle of 4 hours at 50 ℃ X12 times.
The pressure-sensitive adhesive sheet of the present invention is also excellent in handling properties. In the present specification, the handling property of the pressure-sensitive adhesive sheet can be evaluated by bleeding (bleeding value) of the pressure-sensitive adhesive at the time of bonding. Specifically, when the temperature of the pressure part was set to 25 ℃ and the pressure was applied for 5 minutes at a pressure of 0.2MPa, the pressure-sensitive adhesive sheet was evaluated to have a small spread (bleeding value), and the handling property was good. The bleeding value of the pressure-sensitive adhesive sheet is preferably 1.2mm or less, more preferably 1.0mm or less, and still more preferably 0.8mm or less. The bleeding value of the adhesive sheet was evaluated by the method described in examples.
The adhesive sheet of the invention has a tensile stress of 0.3N/mm at a tensile elongation of 2000% before photocrosslinking 2 It is preferably 0.25N/mm 2 Below, more preferably 0.2N/mm 2 The lower, more preferably 0.15N/mm 2 The following, particularly preferably 0.1N/mm 2 The following. When the tensile stress of the pressure-sensitive adhesive sheet is within the above range, a pressure-sensitive adhesive sheet having a level difference following property, durability and handling property can be easily obtained.
Here, the tensile stress at a tensile elongation of 2000% before photocrosslinking of the pressure-sensitive adhesive sheet is a value measured in the following manner. The adhesive sheet was first cut into a length of 50mm and a width (width direction) Amm. In this case, the value of a in the transverse direction (width direction) is 6mm in terms of the thickness (mm) of the adhesive sheet × Amm 2 Is determined. Next, the adhesive sheet was wound in the width direction to prepare a cylindrical sample having a diameter of 2.8mm and a height of 50mm, and the upper end and the lower end of the cylindrical sample up to 10mm were sandwiched between 2 (4 sheets in total) PET films having a thickness of 188 μm, a length of 25mm and a width of 50 mm. Then, this region was set as a chuck portion of a tensile tester, fixed so that the distance between chucks was 30mm, and the tensile was performed at a tensile rate of 300 mm/min under an environment of a measurement temperature of 23 ℃ and a relative humidity of 50% until the tensile elongation became 2000%, and the stress value at this time was taken as a tensile stress.
The tensile elongation in the present specification is a ratio calculated by the following formula.
Tensile elongation (%) (distance between chucks after stretching-distance between chucks before stretching (30 mm))/distance between chucks before stretching (30mm) × 100
When the tensile stress at 2000% tensile elongation of the psa sheet before photocrosslinking is measured as described above, the maximum tensile elongation of the psa sheet before photocrosslinking must be 2000% or more. When the tensile elongation of the pressure-sensitive adhesive sheet before photocrosslinking is less than 2000%, the pressure-sensitive adhesive sheet breaks before the tensile elongation becomes 2000% when the tensile stress is measured. In this case, the stress value obtained in the above measurement is a fracture stress.
The breaking stress of the pressure-sensitive adhesive sheet after photocrosslinking is preferably 1.0N/mm 2 Less than, more preferably 0.9N/mm 2 The lower, more preferably 0.8N/mm 2 The following. The breaking stress after photocrosslinking of the pressure-sensitive adhesive sheet was a value obtained as follows: the cumulative light amount of the adhesive sheet was 2000mJ/cm 2 The method (4) is obtained by irradiating ultraviolet rays and then measuring the tensile stress. In the present specification, the pressure-sensitive adhesive sheet before photocrosslinking is, for example, a pressure-sensitive adhesive sheet having a cumulative light amount of 2000mJ/cm 2 The pressure-sensitive adhesive sheet before being irradiated with ultraviolet light, and the pressure-sensitive adhesive sheet after being photo-crosslinked has a cumulative light amount of, for example, 2000mJ/cm 2 The pressure-sensitive adhesive sheet irradiated with ultraviolet rays. The cumulative amount of ultraviolet light can be set as appropriate to the amount of light with which the adhesive sheet can be completely cured.
The adhesive sheet of the present invention may have a tensile elastic modulus before photocrosslinking of 150kPa to 300kPa, preferably 150kPa to 250 kPa. Here, the tensile elastic modulus of the pressure-sensitive adhesive sheet before photocrosslinking is a value calculated from a stress-strain curve (SS curve) obtained in the measurement of the tensile stress. Specifically, the tensile modulus was determined by calculating the slope from the tensile elongation and stress values of 0% and 5%.
The adhesive sheet of the present invention preferably has a tensile elastic modulus after photocrosslinking of 200kPa to 1000kPa, more preferably 250kPa to 800 kPa. The tensile modulus of elasticity is a cumulative light amount of 2000mJ/cm 2 The tensile modulus of the pressure-sensitive adhesive sheet irradiated with ultraviolet rays.
When the tensile elastic modulus of the pressure-sensitive adhesive sheet before photocrosslinking is represented by a and the tensile elastic modulus of the pressure-sensitive adhesive sheet after photocrosslinking is represented by b, b/a may be less than 3.0, preferably 2.8 or less, more preferably 2.5 or less. When the ratio of the tensile elastic modulus of the pressure-sensitive adhesive sheet before photocrosslinking to the tensile elastic modulus of the pressure-sensitive adhesive sheet before photocrosslinking is within the above range, a pressure-sensitive adhesive sheet having satisfactory level difference following properties, durability and handling properties can be easily obtained.
The gel fraction of the pressure-sensitive adhesive sheet of the present invention before photocrosslinking is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 4.0% or less, even more preferably 3.5% or less, and particularly preferably 2.5% or less. The lower limit of the gel fraction of the pressure-sensitive adhesive sheet is not particularly limited, and may be, for example, 0%. When the gel fraction of the pressure-sensitive adhesive sheet before photocrosslinking is within the above range, a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet having excellent level difference following properties can be obtained.
The gel fraction of the adhesive sheet was measured by the following method.
First, about 0.1g of an adhesive sheet (adhesive layer) was collected in a sample bottle, and 30ml of ethyl acetate was added thereto and shaken for 24 hours. Thereafter, the contents of the sample bottle were separated by filtration through a 150-mesh stainless steel wire mesh, and the residue on the wire mesh was dried at 100 ℃ for 1 hour to measure the dry weight W (g). The gel fraction was determined from the obtained dry weight according to the following formula 1.
Gel fraction (% by mass) x 100 · -formula 1 (dry weight W/collected weight of adhesive sheet) × (dry weight W/collected weight of adhesive sheet) ·
The gel fraction of the pressure-sensitive adhesive sheet of the present invention is as described above, and when the gel fraction is within the above range, the pressure-sensitive adhesive sheet can be said to be in a semi-cured state. Here, the semi-cured state means that the adhesive sheet has photocrosslinkable properties (curing ability by light irradiation). That is, the adhesive sheet of the present invention is a sheet in a soft state before light irradiation (before photocrosslinking).
The gel fraction of the pressure-sensitive adhesive sheet after photocrosslinking of the present invention is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more. The gel fraction of the pressure-sensitive adhesive sheet after photocrosslinking was 2000mJ/cm in cumulative light amount for the pressure-sensitive adhesive sheet 2 The gel fraction of the pressure-sensitive adhesive sheet irradiated with ultraviolet light in the above manner.
The adhesive sheet of the present invention before photocrosslinking has an adhesive strength to glass of preferably 15.0N/25mm or more, more preferably 19.0N/25mm or more, and still more preferably 20.0N/25mm or more. The adhesive strength to glass of the pressure-sensitive adhesive sheet after photocrosslinking is preferably 20.0N/25mm or more, more preferably 24.0N/25mm or more, still more preferably 25.0N/25mm or more, and particularly preferably 27.0N/25mm or more. Here, the glass adhesion of the adhesive sheet is the peel strength when the adhesive sheet is peeled from glass at 180 degrees at a tensile speed of 300 mm/min based on JIS Z0237.
The thickness of the adhesive sheet of the present invention is preferably 5 to 500. mu.m, more preferably 30 to 300. mu.m, and still more preferably 50 to 200. mu.m. By setting the thickness of the pressure-sensitive adhesive sheet within the above range, the level difference following property and the durability can be sufficiently improved. Further, bleeding and stickiness of the adhesive can be suppressed, and handling properties can be improved.
When the pressure-sensitive adhesive sheet of the present invention is used, it is preferable to include a step of irradiating light after the pressure-sensitive adhesive sheet is brought into contact with the surface of an adherend. In addition, when the pressure-sensitive adhesive sheet of the present invention is used, it is preferable to include a heat treatment step at the time of and/or after the contact of the pressure-sensitive adhesive sheet with the surface of the adherend. As described above, the adhesive sheet of the present invention is preferably a hot-melt type adhesive sheet and a post-curing type adhesive sheet.
The adhesive sheet of the present invention is preferably a double-sided adhesive sheet. The double-sided adhesive sheet may be a single-layer double-sided adhesive sheet or a multilayer double-sided adhesive sheet in which a plurality of adhesive layers are laminated. The double-sided adhesive sheet may be a double-sided adhesive sheet having an adhesive layer on both sides of a substrate (preferably a transparent substrate). In this case, examples of the substrate include plastic films such as polystyrene, styrene-acrylic copolymer, acrylic resin, polyethylene terephthalate, polycarbonate, polyether ether ketone, and cellulose triacetate; optical films such as antireflection films and electromagnetic wave shielding films.
The present invention also relates to an adhesive composition capable of forming the adhesive sheet. The adhesive composition is formed into a sheet by a known method to obtain an adhesive sheet.
((meth) acrylic acid copolymer)
The adhesive sheet of the present invention preferably contains a (meth) acrylic copolymer. The (meth) acrylic copolymer is a main polymer contained in the adhesive sheet, and such a polymer is sometimes referred to as a base polymer.
The (meth) acrylic copolymer has an alkyl (meth) acrylate unit. In the present specification, a "unit" is a repeating unit (monomer unit) constituting a polymer. The alkyl (meth) acrylate units are derived from alkyl (meth) acrylates. Examples of the alkyl (meth) acrylate include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, and the like, Isobornyl (meth) acrylate, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.
Further, the (meth) acrylic copolymer may have other acrylic monomer units in addition to the alkyl (meth) acrylate unit. Examples of the other acrylic monomer unit include acrylic monomer units having a crosslinkable functional group, and examples thereof include: a hydroxyl group-containing acrylic monomer unit and a glycidyl group-containing acrylic monomer unit. These monomer units may be 1 kind or 2 or more kinds.
The hydroxyl-containing acrylic monomer unit is derived from a hydroxyl-containing acrylic monomer. Examples of the hydroxyl group-containing acrylic monomer include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, [ (mono-, di-or poly-) alkylene glycol ] esters of (meth) acrylic acid such as mono (diethylene glycol) ester of (meth) acrylic acid, and (meth) acrylic acid lactones such as monocaprolactone (meth) acrylate.
Examples of the glycidyl group-containing acrylic monomer unit include monomer units derived from glycidyl group-containing acrylic monomers such as glycidyl (meth) acrylate.
When the (meth) acrylic copolymer has another acrylic monomer unit other than the alkyl (meth) acrylate unit, the content of the other acrylic monomer unit is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the (meth) acrylic copolymer. Among them, the content of the acrylic monomer unit having a crosslinkable functional group is preferably within the above range. When the content of the other acrylic monomer unit is not less than the lower limit, the cohesive strength can be sufficiently improved, and when the content is not more than the upper limit, sufficient adhesive strength can be easily secured.
The glass transition temperature (Tg) of the (meth) acrylic copolymer may be-50 ℃ or higher, preferably-49 ℃ or higher, more preferably-48 ℃ or higher. The glass transition temperature (Tg) of the (meth) acrylic copolymer is preferably-10 ℃ or lower, more preferably-20 ℃ or lower, still more preferably-30 ℃ or lower, and particularly preferably-40 ℃ or lower. When the glass transition temperature (Tg) of the (meth) acrylic copolymer is in the above range, handling properties of the adhesive sheet can be improved, and processing of the adhesive sheet becomes easy. Further, when the glass transition temperature (Tg) of the (meth) acrylic copolymer is in the above range, the cohesive strength of the adhesive sheet can be further increased, and an adhesive sheet having excellent durability and adhesiveness can be obtained.
The weight average molecular weight (Mw) of the (meth) acrylic copolymer is preferably 25 ten thousand or more, more preferably 26 ten thousand or more, further preferably 28 ten thousand or more, and particularly preferably 30 ten thousand or more. The weight average molecular weight (Mw) of the (meth) acrylic copolymer is preferably 45 ten thousand or less, and more preferably 43 ten thousand or less. When the weight average molecular weight (Mw) of the (meth) acrylic copolymer is within the above range, both the level difference following property and the durability can be satisfied. In general, in the pressure-sensitive adhesive sheet, the level difference following property and the durability are in a trade-off relationship, but in the present invention, by setting the weight average molecular weight of the (meth) acrylic copolymer within the above range, both the level difference following property and the durability can be easily achieved.
The weight average molecular weight of the (meth) acrylic copolymer is a value obtained by measuring by Gel Permeation Chromatography (GPC) and converting into standard polystyrene.
The measurement conditions of Gel Permeation Chromatography (GPC) were as follows.
Solvent: tetrahydrofuran (THF)
Column: shodex KF801, KF803L, KF800L, KF800D (for use by connecting 4 columns manufactured by Showa Denko K.K.)
Column temperature: 40 deg.C
Sample concentration: 0.5% by mass
A detector: RI-2031plus (manufactured by JASCO)
A pump: RI-2080plus (manufactured by JASCO)
Flow rate (flow velocity): 0.8ml/min
Injection amount: 10 μ l
Calibration curve: a calibration curve obtained from 10 samples of polystyrene Shodex standard polystyrene (manufactured by Showa Denko K.K.) having Mw of 1320 to 2500000 was used.
The (meth) acrylic copolymer may be a commercially available one or may be produced by polymerizing an acrylic monomer. As commercially available products, there may be used, for example, OP-9200-1, OP-9200-3, OP-9200-4, OP-9200-5, OP-9200-7 and the like manufactured by Aica Kogyo Company, Limited. In the case of producing a (meth) acrylic copolymer by polymerization, the polymerization method can be appropriately selected from commonly used polymerization methods. Examples of the polymerization method include a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.
(polyfunctional monomer)
The adhesive sheet of the present invention preferably contains a polyfunctional monomer. The polyfunctional monomer is a monomer having 2 or more reactive double bonds in the molecule.
Examples of the polyfunctional monomer include: ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1, 3-butylene glycol di (meth) acrylate, 1, 4-butylene glycol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, 1, 6-hexanediol diacrylate, polybutylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, the diacrylate ester of bisphenol a diglycidyl ether, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, the (meth) acrylate ester of polyhydric alcohols such as pentaerythritol tetra (meth) acrylate, and vinyl methacrylate.
The polyfunctional monomer may be any commercially available one. Examples of commercially available products include ATM-4PL and A-TMM-3L manufactured by Mitsukamura chemical Co., Ltd., and PET-30 manufactured by Nippon Kabushiki Kaisha.
The pressure-sensitive adhesive sheet preferably contains 0.1 to 6 parts by mass of a polyfunctional monomer, more preferably 0.5 to 4 parts by mass, per 100 parts by mass of a (meth) acrylic copolymer. The polyfunctional monomer can be used alone in 1 or a combination of 2 or more, in the case of using 2 or more, preferably the total mass is within the above range.
(photopolymerization initiator)
The adhesive sheet of the present invention preferably contains a photopolymerization initiator. The photopolymerization initiator may be one capable of initiating the polymerization reaction of the polyfunctional monomer by irradiation with light, and is preferably one capable of initiating the polymerization reaction of the polyfunctional monomer by irradiation with ultraviolet light.
Examples of the photopolymerization initiator include: acetophenone initiator, benzoin ether initiator, benzophenone initiator, hydroxyalkylphenone initiator, thioxanthone initiator, amine initiator, and the like. The photopolymerization initiator may be used alone in 1 kind or in combination of 2 or more kinds.
Specific examples of the acetophenone initiator include diethoxyacetophenone and benzildimethylketal.
Specific examples of the benzoin ether initiator include benzoin and benzoin methyl ether.
Specific examples of the benzophenone-based initiator include benzophenone and methyl o-benzoylbenzoate.
Specific examples of the hydroxyalkylphenone initiator include 1-hydroxy-cyclohexyl-phenyl-ketone.
Specific examples of the thioxanthone initiator include 2-isopropylthioxanthone and 2, 4-dimethylthioxanthone.
Specific examples of the amine initiator include triethanolamine and ethyl 4-dimethylbenzoate.
The photopolymerization initiator may be any of those commercially available. Examples of commercially available products include TZT manufactured by IGM Resins and Irgacure184 manufactured by BASF corporation.
The pressure-sensitive adhesive sheet may contain 0.1 to 10 parts by mass of a photopolymerization initiator per 100 parts by mass of the (meth) acrylic copolymer, and preferably contains 0.1 to 3 parts by mass. The photopolymerization initiator may be used alone in 1 kind or in combination of 2 or more kinds, and when 2 or more kinds are used in combination, the total mass is preferably within the above range.
(solvent)
The adhesive sheet of the present invention may contain a solvent. In this case, the solvent is used to improve coating suitability of the adhesive sheet.
Examples of such solvents include: hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene, and dichloropropane; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate, and derivatives thereof.
The solvent may be used alone in 1 kind or in combination of 2 or more kinds. The content of the solvent contained in the adhesive sheet is preferably 80% by mass or less, more preferably 50% by mass or less, relative to the total mass of the adhesive sheet.
(optional Components)
The pressure-sensitive adhesive sheet of the present invention may contain other components than those described above within a range not to impair the effects of the present invention. As the other components, those known as additives for adhesives can be cited. For example, the resin may be selected from plasticizers, antioxidants, metal corrosion inhibitors, tackifiers, silane coupling agents, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and the like, as required.
As the plasticizer, a nonfunctional acrylic polymer may be used. The non-functional acrylic polymer means a polymer composed of only an acrylic monomer unit having no functional group other than an acrylate group, or a polymer composed of an acrylic monomer unit having no functional group other than an acrylate group and a non-acrylic monomer unit having no functional group.
Examples of the acrylic monomer unit having no functional group other than an acrylate group include the same units as the non-crosslinkable (meth) acrylate unit.
Examples of the non-acrylic monomer unit having no functional group include: vinyl carboxylates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, and vinyl benzoate, and styrene.
Examples of the antioxidant include a phenol-based antioxidant, an amine-based antioxidant, a lactone-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant. These antioxidants may be used alone in 1 kind, or may be used in combination of 2 or more kinds.
As the metal anticorrosive agent, benzotriazole-based resins can be mentioned.
Examples of the thickener include: rosin-based resins, terpene-phenol-based resins, coumarone indene-based resins, styrene-based resins, xylene-based resins, phenol-based resins, petroleum resins, and the like.
Examples of the silane coupling agent include: mercapto silane coupling agents, (meth) acrylic silane coupling agents, isocyanate silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, and the like.
Examples of the ultraviolet absorber include benzotriazole compounds and benzophenone compounds.
The adhesive sheet of the present invention preferably contains substantially no thermal crosslinking agent. Here, the content of the thermal crosslinking agent in the adhesive sheet is preferably less than 0.5 part by mass, more preferably 0.3 part by mass or less, further preferably 0.2 part by mass or less, further preferably 0.1 part by mass or less, and particularly preferably 0 part by mass, relative to 100 parts by mass of the (meth) acrylic copolymer. When the content of the thermal crosslinking agent is within the above range, the step following property of the adhesive sheet can be more effectively improved. In addition, when the content of the thermal crosslinking agent is within the above range, the aging step can be omitted when forming the adhesive sheet, and the time required for manufacturing the adhesive sheet can be shortened.
Examples of the thermal crosslinking agent include known thermal crosslinking agents such as isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, and butylated melamine compounds.
(double-sided adhesive sheet with Release sheet)
The present invention may also relate to a double-sided pressure-sensitive adhesive sheet with a release sheet, which includes a release sheet on both sides of the pressure-sensitive adhesive sheet.
Fig. 1 is a schematic cross-sectional view showing an example of a double-sided adhesive sheet with a release sheet according to the present invention. The release-sheet-attached double-sided adhesive sheet 1 includes a double-sided adhesive sheet 11, and a release sheet 12a and a release sheet 12b on both sides thereof. The double-sided adhesive sheet 11 may be a single-layer double-sided adhesive sheet as shown in fig. 1, or may be a multilayer double-sided adhesive sheet in which a plurality of adhesive layers are laminated. The double-sided adhesive sheet 11 may be a double-sided adhesive sheet having an adhesive layer on both sides of a substrate (preferably a transparent substrate).
As shown in fig. 1, the surface of the double-sided adhesive sheet 11 is preferably covered with a release sheet 12a and a release sheet 12 b. Examples of the release sheet include: a releasable laminate sheet having a release sheet substrate and a release agent layer provided on one surface of the release sheet substrate, or a polyolefin film such as a polyethylene film or a polypropylene film as a low-polarity substrate.
Paper or a polymer film is used as a base material for a release sheet in the releasable laminate sheet. Examples of the release agent constituting the release agent layer include general-purpose addition or condensation type silicone release agents and long chain alkyl group-containing compounds. In particular, an addition silicone release agent having high reactivity is preferably used.
Specific examples of the silicone-based release agent include: BY24-4527 and SD-7220 manufactured BY Dow Corning Toray Silicone Co., Ltd., and KS-3600, KS-774 and X62-2600 manufactured BY shin-Etsu chemical Co., Ltd. Further, it is preferable that the silicone-based release agent contains SiO as a component 2 Unit, and (CH) 3 ) 3 SiO 1/2 Unit or CH 2 ＝CH(CH 3 )SiO 1/2 A silicone resin of a unit of an organosilicon compound. Specific examples of the Silicone resin include BY24-843, SD-7292, and SHR-1404 manufactured BY Dow Corning Toray Silicone Co., Ltd., KS-3800 and X92-183 manufactured BY shin-Etsu chemical Co., Ltd.
As the releasable laminate sheet, a commercially available product can be used. Examples thereof include: a heavy release Film of polyethylene terephthalate Film produced by Teijin Dupont Film Japan Limited, and a light release Film of polyethylene terephthalate Film produced by Teijin Dupont Film Japan Limited.
The pressure-sensitive adhesive sheet of the present invention preferably has 1 pair of release sheets having different release forces. That is, in the release sheet, it is preferable that the release properties of the release sheet 12a and the release sheet 12b are different from each other in order to facilitate the release. When the releasability from one side is different from the releasability from the other side, it is easy to peel only the release sheet having high releasability first. In this case, the peelability of the release sheet 12a and the release sheet 12b may be adjusted according to the bonding method and the bonding procedure.
(method of producing laminate)
When the pressure-sensitive adhesive sheet of the present invention is used, the pressure-sensitive adhesive sheet is brought into contact with the surface of an adherend. After the pressure-sensitive adhesive sheet is brought into contact with the surface of the adherend, a step of irradiating with light is preferably included. That is, the method for producing a laminate of the present invention preferably includes: a bonding step of bringing the pressure-sensitive adhesive sheet into contact with the surface of an adherend, and a light irradiation step.
The method for producing a laminate of the present invention may further include a heat treatment step at the time of and/or after the contact of the pressure-sensitive adhesive sheet with the surface of the adherend. In this case, the heat treatment step is followed by a step of irradiating with light. That is, the method for producing a laminate of the present invention may include a bonding step of bringing a pressure-sensitive adhesive sheet into contact with an adherend surface and a light irradiation step, and may further include at least one of the following steps (a) and (b).
In the step (a), a heat treatment is performed in the bonding step.
The step (b) includes a defoaming step in the steps subsequent to the bonding step and prior to the light irradiation step, and the heating treatment is performed in the defoaming step.
In the bonding step, the pressure-sensitive adhesive sheet is bonded to an adherend. Examples of the bonding method include a roll bonding method and a vacuum bonding method.
In the heat treatment in the above-mentioned step (a) and step (b), it is preferable to perform the heat treatment at 40 to 59 ℃. The heating temperature is preferably 50 to 59 ℃. By providing such a heat treatment step in the production process of the laminate, the flexibility of the adhesive sheet or double-sided adhesive sheet can be further improved, and the step can be easily followed.
Conventionally, when a hot-melt adhesive sheet is used, it is a common method to perform a heat treatment at 60 ℃ or higher, but such a heat treatment at a high temperature may damage an adherend. In the method for producing a laminate of the present invention, the treatment temperature at the time of heat treatment in the bonding step and/or the step subsequent to the bonding step can be kept lower than usual, and sufficient level difference following properties can be obtained even in this case, and therefore, the risk of damaging the adherend can be kept extremely low. Further, the photothermal cost in the production of the laminate can be suppressed, and the production efficiency of the laminate can be further effectively improved.
The heat treatment at 40 to 59 ℃ is preferably performed in the bonding step or the defoaming step. The heat treatment may be performed in two steps, i.e., the bonding step and the defoaming step. Examples of the bonding step include a roll bonding step and a vacuum bonding step. The defoaming step may be, for example, an autoclave treatment step. That is, the heat treatment at 40 to 59 ℃ is preferably performed in at least 1 step selected from the group consisting of an autoclave treatment step, a roll bonding step, and a vacuum bonding step. In this case, the heating set temperature in the autoclave treatment step, the roller bonding step, and the vacuum bonding step is preferably 40 to 59 ℃. The heat treatment is also preferably performed in two steps, i.e., the bonding step and the defoaming step.
In the light irradiation step, light is irradiated to the adherend of the pressure-sensitive adhesive sheet or double-sided pressure-sensitive adhesive sheet and the adherend. In this manner, the light irradiation step may be referred to as a post-curing step. By post-curing the pressure-sensitive adhesive sheet with light, the cohesive force of the pressure-sensitive adhesive is improved, and the adhesiveness to an adherend is improved.
The light irradiation step is preferably a step of irradiating ultraviolet rays.
Examples of the light source of ultraviolet rays include a high-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, and an electrodeless ultraviolet lamp.
As the electron beam, for example, electron beams emitted from various electron beam accelerators such as a kochroft-Walton (Cockcroft-Walton) type, a Van der Graaff (Van de Graaff) type, a resonance transformer type, an insulating core transformer type, a linear type, a high-frequency high-voltage accelerator type, and a high-frequency type can be used.
The ultraviolet irradiation power is preferably such that the cumulative light amount is 100 to 10000mJ/cm 2 More preferably 500 to 5000mJ/cm 2 。
(laminated body)
The laminate produced by the above production method is provided with a post-cured pressure-sensitive adhesive sheet and an adherend. The laminate of the present invention preferably has adherends on both sides of the post-cured pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet of the present invention is particularly preferably used for bonding an adherend having a level difference portion.
Fig. 2 is a cross-sectional view showing an example of a structure of a laminate 30 obtained by bonding a double-sided adhesive sheet 11 of the present invention to an adherend 31 having a level difference portion 32. As shown in fig. 2, the adherend 31 has a level difference portion 32. The height difference part 32 may have a thickness of 5 to 60 μm. As described above, the double-sided pressure-sensitive adhesive sheet 11 of the present invention can be used for bonding an adherend having a level difference portion. The double-sided pressure-sensitive adhesive sheet 11 of the present invention can be used for bonding an adherend having a thickness of 35 μm or more, particularly in the step 32.
The adherend 31 is preferably an optical member. Examples of the optical member include components in optical products such as touch panels and image display devices.
Examples of the constituent members of the touch panel include: an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on a surface of a glass plate, a transparent conductive film in which a conductive polymer is coated on a transparent resin film, a hard coat film, a fingerprint resistant film, and the like. The double-sided adhesive sheet of the present invention is preferably used for sensor lamination of a touch panel, and more preferably used for sensor lamination of a touch panel using a stylus pen. From this viewpoint, as the adherend of the double-sided pressure-sensitive adhesive sheet of the present invention, an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on a surface of a glass plate, and a transparent conductive film in which a conductive polymer is coated on a transparent resin film are preferable.
Examples of the constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device.
Examples of the material used for these members include: glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, cellulose triacetate, polyimide, cellulose acylate, and the like.
Examples
The features of the present invention will be described in more detail below with reference to examples and comparative examples. The materials, the amounts used, the ratios, the contents of the treatments, the procedures of the treatments, and the like shown in the following examples can be appropriately modified within the scope not departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being limited to the specific examples shown below.
[ example 1]
(preparation of adhesive composition)
100 parts by mass of a (meth) acrylic copolymer (OP-9200-3, manufactured by Aica Kogyo Company, Limited), 2 parts by mass of pentaerythritol triacrylate (ATM-4 PL, manufactured by Newzhou chemical Co., Ltd.) as a polyfunctional monomer, and 1.5 parts by mass of a photopolymerization initiator (TZT, manufactured by IGM Resins) were mixed, and the mixture was stirred for 3 minutes under atmospheric pressure using a stirrer (SK-200 TVS, manufactured by SHASHIN KAGAKU Co., Ltd.) to prepare an adhesive composition.
(preparation of adhesive sheet)
The pressure-sensitive adhesive composition obtained in the above manner was uniformly applied by an applicator to a surface of a38 μm thick polyethylene terephthalate film (1 st release sheet) (Oji F-Tex Co., Ltd.; 38RL-07(2) manufactured by Ltd.) having a release agent layer treated with a silicone-based release agent so that the coating film thickness after drying was 100 μm. Thereafter, the sheet was dried in an air circulation type constant temperature oven at 100 ℃ for 3 minutes to form an adhesive layer on the surface of the 1 st release sheet. Then, a 2 nd release sheet (38 RL-07(L) manufactured by Oji F-Tex Co., Ltd.) having a thickness of 38 μm was laminated on the surface of the pressure-sensitive adhesive layer to obtain a double-sided pressure-sensitive adhesive sheet with a release sheet having a configuration of 1 st release sheet/pressure-sensitive adhesive layer/2 nd release sheet in which the pressure-sensitive adhesive layer was sandwiched between 1 pair of release sheets having a poor release force.
[ example 2]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the amount of the polyfunctional monomer added in example 1 (preparation of the adhesive composition) was changed to 3 parts by mass.
[ example 3]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the blending amount of the polyfunctional monomer in example 1 (preparation of the adhesive composition) was changed to 4 parts by mass.
[ example 4]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the amount of the photopolymerization initiator added in example 1 (preparation of adhesive composition) was changed to 0.7 parts by mass.
[ example 5]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the amount of the photopolymerization initiator added was changed to 3 parts by mass in example 1 (preparation of adhesive composition).
[ example 6]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-1 (manufactured by Aica Kogyo Company, limited.) and the amount of the polyfunctional monomer to be added was changed to 1 part by mass in example 1 (preparation of adhesive composition).
[ example 7]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 6 except that the amount of the polyfunctional monomer added in example 6 (preparation of the adhesive composition) was changed to 2 parts by mass.
[ example 8]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-5 (manufactured by Aica Kogyo Company, limited.) in example 1 (preparation of adhesive composition).
[ example 9]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 8 except that the blending amount of the polyfunctional monomer in example 8 (preparation of the adhesive composition) was changed to 4 parts by mass.
[ example 10]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 9 except that the amount of the photopolymerization initiator added was changed to 3 parts by mass in example 9 (preparation of adhesive composition).
[ example 11]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 8 except that the amount of the polyfunctional monomer added in example 8 (preparation of the adhesive composition) was changed to 3 parts by mass.
[ example 12]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-7 (manufactured by Aica Kogyo Company, limited.) in example 1 (preparation of adhesive composition).
[ example 13]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 12 except that the blending amount of the polyfunctional monomer in example 12 (preparation of the adhesive composition) was changed to 4 parts by mass.
[ example 14]
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-4 (manufactured by Aica Kogyo Company, limited.) in example 1 (preparation of adhesive composition).
[ example 15]
A pressure-sensitive adhesive composition was prepared in the same manner as in example 1 except that 100 parts by mass of a (meth) acrylic copolymer (OP-9200-3, manufactured by Limited, Inc.), 1 part by mass of pentaerythritol triacrylate (PET-30, manufactured by Nippon Kagaku Co., Ltd.) as a polyfunctional monomer, and 1 part by mass of a photopolymerization initiator (Irgacure 184, manufactured by BASF) were mixed and stirred for 3 minutes under atmospheric pressure using a stirrer (SK-200 TVS, manufactured by SHASHIN KAGAKU Co., Ltd.) to prepare a double-sided pressure-sensitive adhesive sheet with a release sheet.
[ example 16]
A double-sided pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in example 1, except that a pressure-sensitive adhesive composition was obtained in the same manner as in example 1 and uniformly applied by an applicator in (preparation of pressure-sensitive adhesive sheet) such that the coating film thickness after drying was 150 μm.
[ example 17]
A double-sided adhesive sheet with a release sheet was obtained in the same manner as in example 1, except that an adhesive composition was obtained in the same manner as in example 7 and uniformly applied by an applicator in (preparation of adhesive sheet) such that the coating film thickness after drying was 150 μm.
[ example 18]
A double-sided adhesive sheet with a release sheet was obtained in the same manner as in example 1, except that an adhesive composition was obtained in the same manner as in example 7 and uniformly applied by an applicator in (preparation of adhesive sheet) such that the coating film thickness after drying was 75 μm.
Comparative example 1
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the blending amount of the polyfunctional monomer in example 1 (preparation of the adhesive composition) was changed to 7 parts by mass.
Comparative example 2
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in comparative example 1, except that the polyfunctional monomer was changed to PET-30 manufactured by japan chemical corporation in comparative example 1 (preparation of adhesive composition).
Comparative example 3
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-6 (manufactured by Aica Kogyo Company, limited.) in example 1 (preparation of adhesive composition).
Comparative example 4
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-9 (manufactured by Aica Kogyo Company, limited.) and the amount of the polyfunctional monomer to be added was changed to 1 part by mass in example 1 (preparation of adhesive composition).
Comparative example 5
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-9 (manufactured by Aica Kogyo Company, limited.) in example 1 (preparation of adhesive composition).
Comparative example 6
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-9 (manufactured by Aica Kogyo Company, limited.) and the amount of the polyfunctional monomer was changed to 4 parts by mass in example 1 (preparation of adhesive composition).
Comparative example 7
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-8 (manufactured by Aica Kogyo Company, limited.) in example 1 (preparation of adhesive composition).
Comparative example 8
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-8 (manufactured by Aica Kogyo Company, limited.) and the amount of the polyfunctional monomer was changed to 4 parts by mass in example 1 (preparation of adhesive composition).
Comparative example 9
An adhesive composition and a double-sided adhesive sheet with a release sheet were obtained in the same manner as in example 1 except that the (meth) acrylic copolymer was changed to OP-9200-5 (manufactured by Aica Kogyo Company, limited.) and the amount of the polyfunctional monomer to be added was changed to 1 part by mass in example 1 (preparation of adhesive composition).
(measurement)
< tensile stress, maximum elongation at tensile >
The tensile stress of the adhesive sheet before photocrosslinking was measured in the following manner. First, the double-sided adhesive sheets with release sheets obtained in examples and comparative examples were cut into piecesLongitudinal 50mm, transverse (width direction) Amm. In this case, the value of a in the transverse direction (width direction) is 6mm in terms of the thickness (mm) × Amm of the adhesive sheet 2 Is determined. Subsequently, the 1 st release sheet was peeled off, and only the adhesive sheet was wound in the width direction to prepare a cylindrical sample having a diameter of 2.8mm and a height of 50mm, and the region from the upper end and the lower end of the cylindrical sample up to 10mm was sandwiched by2 (4 sheets in total) PET films having a thickness of 188 μm, a length of 25mm, and a width of 50mm, and the region was fixed as a chuck portion of a tensile tester so that the distance between chucks was 30 mm. Thereafter, the resulting film was stretched at a stretching speed of 300 mm/min under an environment of a measurement temperature of 23 ℃ and a relative humidity of 50% until the tensile elongation became 2000%. The stress value at this time was taken as tensile stress.
With respect to the tensile stress of the adhesive sheet after photo-crosslinking, the cumulative light amount from the 1 st release sheet side of the cut double-sided adhesive sheet with release sheet was 2000mJ/cm 2 The cylindrical sample was obtained after irradiation with ultraviolet rays in the above-mentioned manner, and the measurement was performed by the same method.
In the table, the value with the index (—) is the breaking point before the tensile elongation of the cylindrical sample reaches 2000%, and the stress at the breaking point is recorded. The tensile maximum elongation of the sample broken before the tensile elongation of the cylindrical sample reached 2000% is shown in the table.
< tensile elastic modulus >
The tensile elastic modulus of the pressure-sensitive adhesive sheet was calculated from the stress-strain curve (SS curve) obtained in the measurement of < tensile stress >. Specifically, the tensile modulus was determined by calculating the slope from the tensile elongation and stress values of 0% and 5%.
< gel fraction >
About 0.1g of each adhesive sheet was collected before and after photocrosslinking (before and after ultraviolet irradiation) in a sample bottle, and 30ml of ethyl acetate was added thereto and shaken for 24 hours. Thereafter, the contents of the sample bottle were separated by filtration through a 150-mesh stainless steel wire mesh, and the residue on the wire mesh was dried at 100 ℃ for 1 hour to measure the dry weight W (g). The gel fraction was determined from the obtained dry weight according to the following formula 1.
Gel fraction (% by mass) (dry weight W/weight of adhesive sheet) X100. cndot. formula 1
< adhesion >
The 2 nd release sheet of the double-sided pressure-sensitive adhesive sheet with a release sheet was peeled off, and the resultant was bonded to a PET film (Cosmoshine A4300100 μm, manufactured by Toyo Boseki Co., Ltd.), and cut into pieces of 25mm X150 mm. Thereafter, the 1 st release sheet was peeled off, pressed against a glass plate with a 2kg load roller, and left to stand at room temperature for 30 minutes. Thereafter, the peel strength at 180 degrees peel at a tensile rate of 300 mm/min was measured as the adhesive force based on JIS Z0237 using a tensile tester (model: Autograph AGS-J, Shimadzu corporation).
(evaluation)
< method for producing laminate >
An ultraviolet-curable ink was screen-printed on the surface of a glass plate (90 mm in length × 50mm in width × 0.5mm in thickness) in a frame shape (90 mm in length × 50mm in width, 5mm in width) so as to have a coating thickness of 5 μm. Subsequently, the printed ultraviolet curable ink is cured by irradiation with ultraviolet light. This step was repeated a predetermined number of times to obtain a printed step glass having a step portion with a thickness of 35 μm.
The double-sided adhesive sheets with release sheets obtained in examples and comparative examples were cut into a shape of 90mm in length × 50mm in width, the 1 st release sheet was peeled off, and the adhesive sheet (adhesive layer) was attached to the entire frame-shaped printing surface of the printing height difference glass by using a laminator (YOUBON co., ltd., IKO-650 EMT). Thereafter, the 2 nd release sheet was peeled off, and a glass plate (90 mm in length × 50mm in width × 0.5mm in thickness) was bonded to the exposed adhesive sheet (adhesive layer) using a vacuum bonding machine (manufactured by Sun engineering Co., Ltd.: vacuum laminating apparatus (JE 2020B-MVH)). The bonding conditions at this time were: at 40 deg.C, weak pressurizing force of 0.6kN, strong pressurizing force of 1.2kN, vacuum pressure of 100Pa, and pressurizing holding time of 10 seconds. Then, defoaming treatment (autoclave treatment: 40 ℃, 0.5MPa, 10 minutes) was performed, and then the cumulative light amount was 2000mJ/cm from the printing height difference glass side by an ultraviolet irradiation device (EYE GRAPHICS CO., LTD., ECS-301G1) 2 The laminate was obtained by irradiating ultraviolet rays.
< evaluation of following Property by height Difference >
The print level difference portion of the laminate was observed with a microscope (magnification: 25 times) and evaluated according to the following criteria.
O: the surface of the bonded layer is completely filled with no bubbles
X: the height difference bonding surface is observed with bubbles and the height difference is not buried
< durability >
The laminate was set in a QUV tester (Q-LAB Co., Ltd.) at 0.8W/m 2 At 80 ℃ for 4 hours and at 0.53W/m 2 The samples were irradiated with ultraviolet (UV-A) light at 50 ℃ for 4 hours in cycles X12 times, and the samples were examined with a microscope (magnification: 25 times) for the presence of bubbles in the whole sample and evaluated according to the following criteria. The irradiation with ultraviolet light is performed from the printing step glass side.
O: no bubbles were generated at all.
X: bubble and peeling are generated.
< handlability >
The sheet was cut out from the double-sided adhesive sheet with a release sheet in a size of 30mm in length by 30mm in width. One side of the release sheet of the sheet was peeled off, and the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) exposed by peeling was attached to the silicone-treated surface of a release sheet (A71100 μm: Teijin Dupont Film Japan Limited) cut in advance in a 50mm square. Thereafter, the other release sheet remaining on the sheet was covered with a silicone-treated surface which was additionally cut into a 50mm square release sheet (A38# 50: Teijin Dupont Film Japan Limited). Thereafter, the temperature of the press part was set to 25 ℃ and the press was pressurized at 0.2MPa for 5 minutes using a press tester (manufactured by Toyo Seiki Seisaku-Sho Ltd.: MP-WNL). Thereafter, the distance of the adhesive layer spreading outward from each side of the release sheet was measured. Specifically, the distance (maximum distance) between each side of the release sheet and the point at which the pressure-sensitive adhesive layer spreads most is measured, and the average value of the four sides is defined as the bleeding value.
[ Table 1]
Figure BDA0002545188340000251
[ Table 2]
Figure BDA0002545188340000261
[ Table 3]
Figure BDA0002545188340000271
It is understood that the pressure-sensitive adhesive sheets obtained in the examples are excellent in level difference following property and durability, and can be handled well.
In comparative examples 4 to 8, no evaluation of durability was performed because bubbles were generated on the level difference bonded surface before the durability test was performed.
Description of the reference numerals
1 double-sided pressure-sensitive adhesive sheet with Release sheet
11 double-sided adhesive sheet
12a Release sheet
12b Release sheet
30 laminated body
31 adherend
32 height difference part

Claims (6)

1. An adhesive sheet having photo-crosslinking properties,
the adhesive sheet has a tensile stress of 0.3N/mm at a tensile elongation of 2000% before photocrosslinking 2 In the following, the following description is given,
the tensile elastic modulus before photocrosslinking is 150kPa to 300kPa,
b/a is less than 3.0 when the tensile elastic modulus before photocrosslinking is a and the tensile elastic modulus after photocrosslinking is b;
the gel fraction before photocrosslinking is 5.0% or less,
the composition contains a (meth) acrylic copolymer having a glass transition temperature Tg of-50 ℃ to-40 ℃ and a weight average molecular weight of 25 to 45 ten thousand, and contains 0.1 to 6 parts by mass of a polyfunctional monomer and 0.1 to 10 parts by mass of a photopolymerization initiator which initiates polymerization of the polyfunctional monomer by light irradiation, relative to 100 parts by mass of the (meth) acrylic copolymer.
2. The adhesive sheet according to claim 1, wherein the gel fraction after photocrosslinking is 50% or more.
3. The adhesive sheet according to any one of claims 1 to 2, wherein the thickness is 50 to 200 μm.
4. A double-sided pressure-sensitive adhesive sheet with a release sheet, wherein the pressure-sensitive adhesive sheet according to any one of claims 1 to 3 is provided with a release sheet on both sides thereof.
5. A method for manufacturing a laminate, comprising the steps of: a bonding step of bringing the pressure-sensitive adhesive sheet according to any one of claims 1 to 3 into contact with the surface of an adherend, and a light irradiation step.
6. The method for producing a laminate according to claim 5, wherein the adherend is an optical member.
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